The present application claims priority under 35 USC 119 to Japanese Patent Application Ser. No. 2001-314826 filed on Oct. 12, 2001 the entire contents thereof is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to an orifice of a fluid passage and an orifice clogging preventing mechanism applied to a hydraulic control unit of an internal combustion engine provided with a hydraulic type automatic transmission and other such devices.
2. Description of Background Art
Heretofore, an orifice and an orifice clogging preventing mechanism were provided, respectively, as separate mechanisms from a hydraulic control unit.
An object of the present invention is to provide a compact orifice and an orifice clogging preventing mechanism, respectively, that are integrated with a hydraulic control unit in the hydraulic control unit of an internal combustion engine provided with a hydraulic type automatic transmission.
The present invention provides an orifice of a fluid passage of a hydraulic control unit formed by inserting a plate between two parts and an orifice clogging preventing mechanism and includes one groove type fluid passage formed in the first part that is in communication with a groove type fluid passage formed in the second part via a group of small holes formed on the plate. The groove type fluid passage in the second part is in communication with a separate groove type fluid passage in the first part from the groove type fluid passage in the first part via an orifice formed on the plate and the diameter of each small hole in the group of small holes is set to a smaller value than that of the orifice.
As the invention is configured as described above, an orifice having a very compact structure and an orifice clogging preventing mechanism, respectively, can be installed that are integrated with the hydraulic control unit and as foreign matter which may cause a clogging of the orifice is picked by any one of the small holes in the group of small holes and does not reach the orifice even if the foreign matter is mixed in a fluid. Thus, the clogging of the orifice is prevented.
The present invention is directed to a hydraulic control unit which is a valve body of a hydraulic control unit of an internal combustion engine provided with a hydraulic type automatic transmission. Two parts are arranged to be adjacent to two layer components of layer components forming the valve body. Thus, a compact valve body for the hydraulic control unit can be provided.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.